Hypothermia defined:
"A decrease in the core body temperature to a level at which normal muscular and cerebral functions are impaired".
Two types:
- Sudden Onset - rapid chilling from cold water exposure.
- Long Onset - progressive exposure over a period of time. Usually occurs with exposure below 50° wind, wet from rain, sea spray or perspiration all create problems. May develop silent hypothermia with gradual onset of physical and mental fatigue unaccompanied by shivering.
Conditions Leading to Hypothermia
Cold temperatures
Improper clothing and equipment
Wetness
Fatigue, exhaustion
Dehydration
Poor food intake
No knowledge of hypothermia
Alcohol intake - causes vasodilatation leading to increased heat loss
What are hypothermia temperatures
Below freezing
40° - Ex. Shenandoahs, wind and rain
60° - Ex. Rayanna and hurricane
Any temperature less than 98.6° can be linked to hypothermia (ex. hypothermia in the elderly in cold houses) or peripheral circulation problems such as trench foot and frostbite.
Signs and Symptoms of Hypothermia
Watch for the - Umbles - stumbles, mumbles, fumbles, and grumbles which show changes in motor coordination and levels of consciousness
Mild Hypothermia
Core temperature 98.6 - 96°F.
Shivering - not under voluntary control
Can't do complex motor functions (ice climbing or skiing) can still walk & talk
Vasoconstriction to periphery
Moderate Hypothermia
Core temperature 95 - 93°F.
Dazed consciousness
Loss of fine motor coordination - particularly in hands - can't zip up parka, due to restricted peripheral blood flow
Slurred speech
Violent shivering
Irrational behavior - Paradoxical Undressing - person starts to take off clothing, unaware he/she is cold
I don't care attitude - flattened affect
Severe Hypothermia
Core temperature 92 - 86° and below (immediately life threatening).
Shivering occurs in waves, violent then pause, pauses get longer until shivering finally ceases - because the heat output from burning glycogen in the muscles is not sufficient to counteract the continually dropping core temperature, the body shuts down on shivering to conserve glucose
Person falls to the ground, can't walk, curls up into a fetal position to conserve heat
Muscle rigidity develops - because peripheral blood flow is reduced and due to lactic acid and CO2 buildup in the muscles
Skin is pale
Pupils dilate
Pulse rate decreases
At 90° the body tries to move into hibernation, shutting down all peripheral blood flow and reducing breathing rate and heart rate.
At 86° the body is in a state of "metabolic icebox." The person looks dead but is still alive.
Death from Hypothermia
Breathing becomes erratic and very shallow
Semi-conscious
Cardiac arrhythmia's develop, any sudden shock may set off Ventricular Fibrillation (uncoordinated heart rhythm - quickly leads to death)
Heart stops, death
How to Assess if someone is Hypothermic
If shivering can be stopped voluntarily = mild hypothermia
Ask the person a question that requires higher reasoning in the brain (count backwards from 100 by 9's). If the person is hypothermic, they won't be able to do it. [Note: there are also other conditions such as altitude sickness that can also cause the same condition.]
If shivering cannot be stopped voluntarily = moderate - severe hypothermia.
If you can't get a radial pulse at the wrist it indicates a core temperature below 90 - 86°.
The person may be curled up in a fetal position. Try to open their arm up from the fetal position, if it curls back up, the person is alive. Dead muscles won't contract - only live muscles.
An old Emergency Room adage: A person is never dead until they are warm and dead. This means that even if you don't have vital signs you assume the person is still alive and treat them for hypothermia. Remember, people have survived sustained periods of hypothermia and drowning from cold water. Cold water induced Mammalian reflex slows heart rate, oxygen and energy requirements in an effort to preserve life.